Sinusoidal issue of ADC signals using TI Delfino F28379D LaunchPad

Hello,

I'm using the TI Delfino F28379D LaunchPad with Simulink to receive an acquisition of sinusoidal current signals of three phase induction motor throughout a control drive. the timer period of epwm is 10kHz based on the DSP clocking calculation equation (100e6)/(2*5000) = 10kHz, the SOCx acquisition window of the ADC is set to 200, the SCIA baud rate is set to 115200, and the Serial port is over a USB.

In order to visualize the expected sine wave of current signals. The issue is how to reduce or cancel these horrific squares that come with the current signal via current sensors during the external mode. This issue significantly impacted the rest of my measurements.

Any suggestions on how to represent a clearer sinusoidal signal?

Any assistance will be greatly appreciated.

Mohamed Elgbaily

Here the signal obtained using the external mode as a signal and three phase.

[Nathan Hardenberg]

Just an idea, but what is your "Fixed-step size (fundamental sample time)" in your simulink model? If this is to high, not enough samples get read. You can try lowering it and that will maybe help

[Mohamed Elgbaily]

Thank you so much Nathan Hardenberg for your kind reply

yes, my Fixed-step size (fundamental sample time) is 1/5000 which is 2e-4. just to let you know that if I need to change the sample time, then my calculation needs to be changed in some points such as the Lowpass filter as it is mainly based on sample time that corresponds with the cutoff frequency.

many thanks

[Nathan Hardenberg]

Okay, that should be low enough! But this lead me to another idea. Maybe your baud rate is to small. When sending three double values that are

If you want to do this 5000 times a second, that are And thats only the three values, nothing else.

Since baudrate equals bitrate when communitating in binary this would not be enough to send you the values fast enough. Can you try to increase the baudrate to 921600?

[Mohamed Elgbaily]

Hi Nathan,

I greatly appreciate your assistance and explanation; it was very helpful. Currently, the signal has clearly improved with the increased the baudrate to 921600. However, the execution time of the external mode became slower. I increased the SOCx acquisition window of the ADC to 400, which sometimes helps but still results in a delayed response when attempting to modify any system parameters while the external mode is operating.

I was wondering if there are any settings in the DSP configuration to reduce this slow response.

Many thaks

[Nathan Hardenberg]

I'm not quite sure if I understand correctly what you want. But it is obious, that the execution-time gets solwer, since you have to now communicate much more. When attempting to modify parameters on the fly, it also seems obvious, that there is a bit of a communication delay.

But I don't think I can help you much further. To answer your current question one would probably need more info about your specific problem. And also I'm not that deep into MPU programming to help you (i think). If this bothers you much more, maybe think about asking a new question

Answer 1

[Nathan Hardenberg]

Here the results from the comments

Possible fixes:

• Reducing "Fixed-step size (fundamental sample time)"
• Increase baud rate. Here is a list of common baud rates (https://lucidar.me/en/serialib/most-used-baud-rates-table/)

[Mohamed Elgbaily]

Yes, that is right,

thank you Nathan for your precious help